1. Field of the Invention
The present invention relates generally to improvements in and methods for operating a digester. More particularly, but not by way of limitation, the invention relates to an improved digester discharge apparatus and method for discharging a digester.
2. Brief Description of the Prior Art
In the past, various forms of vessels constructed to facilitate the digestion of certain materials have been proposed. Some of these vessels have included various types of devices constructed to effect the discharge of the material retained within the process vessel.
U.S. Pat. No. 2,297,311, issued to Mead, et al. discloses a device for pumping a slurry from a feed tank wherein a secondary fluid is fed into the pump suction to reduce the solids content in the suction line.
U.S. Pat. No. 2,661,244, issued to Baily, discloses an apparatus for feeding solid particulate material by diluting the material to a suspension of light density so the material can be transported through pipelines. U.S. Pat. No. 3,314,730, issued to Anderson, et al., discloses forming a stable suspension of granular phosphate in water for transportation via pipelines wherein the solid materials are discharged from hoppers into a water intake line.
U.S. Pat. No. 3,552,799, issued to Koranda, discloses a device for unloading dry materials from a railroad car wherein a liquid is discharged into the railroad car and into contact with the dry material, thereby creating a slurry within the railroad car for facilitating the removal of the material.
U.S. Pat. No. 2,239,608, issued to Huzenlaub, et al., discloses a rotatably mounted vessel wherein water impregnation, steam treatment or air and fluid evacuation are utilized to prevent clogging of the orifices.
U.S. Pat. No. 3,400,984, issued to Shellene, et al., discloses a system for continuously pumping a highly viscous fluid stream containing solids such as wood chips, coal or potash. The patent states that a solid may be pumped through a pipeline by admixing fragmentized particles of the solid with a fluid carrier. In that patent, the slurry is diluted to a pumping consistency; the apparatus includes a back-flushing system for periodically cleaning the downstream filler apparatus.
U.S. Pat. No. 2,306,926, issued to Allen, discloses solid lumps of material being conveyed hydraulically via a water inlet pipe into a sump. A pump is connected to the sump for pumping the solid material therefrom.
U.S. Pat. No. 3,799,620, issued to Robinson, et al., discloses a railroad car carrying particulate material wherein the car is positioned over a pit and a nozzle is elevated into contact with the railroad car, a liquid nozzle being inserted within the railroad car via the nozzle for releasing high pressure steam and forming a pumpable slurry with the particulate material. The slurry is discharged from the railroad car via gravity.
U.S. Pat. No. 3,512,842, issued to Milewski, et al., discloses a method for unloading dry bulk powder from a hopper car.
Other devices and methods generally related to the movement of solid materials through a conduit or the like are disclosed in the following patents: U.S. Pat. Nos. 2,000,696, issued to Friend, et al.; 2,655,287, issued to Campbell; 3,151,845, issued to Leuze; 697,688, issued to Stelzer; 673,167, issued to Giffen; 3,749,370, issued to Clech, et al.; 3,547,497, issued to Bolger; 2,690,715, issued to Pope; 2,363,177, issued to Haffner; 2,917,768, issued to Walberer; 2,474,006, issued to Maycock; 2,089,535, issued to Cave; 3,545,619, issued to Ettlich, et al.; 2,076,321, issued to Pick; 1,372,119, issued to Congleton, Dec'd.; 3,787,035, issued to Bryson, Jr., et al.; 3,527,384, issued to Susugu Koyama, et al.; French Pat. Nos. 881,824; 2,009,048; Great Britian Pat. Nos. 177,628; 110,609, issued to Bell; Swiss Pat. No. 431,375.